This invention relates to a pedal parking brake device which actuates a parking brake of the wheels of a car or the like, and performs a release thereof.
Heretofore, as such kind of a pedal parking brake device there exists a brake device as shown in FIG. 10 through FIG. 14. In this brake device, a brake pedal 11 is attached, at its base portion, to a supporting shaft 13 fixed to a base plate 12 rotatably and being energized, in a return direction (a direction), by aid of a return spring 14.
A ratchet 15 is attached to the supporting shaft 13 rotatably, said ratchet 15 being connected to one end of a brake cable 16.
A cam plate 17 is provided with a circular cam surface 17a at the top end of the cam plate 17 and the base portion thereof is fixed to the supporting shaft 13.
Further, the brake pedal 11 is provided with a ratchet pawl 18 energized in a latching direction of the ratchet 15 and the base plate 12 is provided with a locking pawl 19 energized in a latching direction of the ratchet 15. The locking pawl 19 is connected to an end of a release cable 20.
In a conventional brake device, when the brake pedal 11 is rotated in b direction by stepping on the pedal brake 11 with the foot from an initial state (FIG. 10) wherein the ratchet pawl 18 is released from latching with ratchet 15 by abutting the top end thereof against the cam surface 17a of the cam plate, the ratchet pawl 18 rotates integrally with the pedal 11 whereby the top end thereof comes off from the cam surface 17a. The ratchet pawl 18, which comes off from the cam surface 17a, latches with the ratchet 15 to rotate the ratchet 15 in the same direction as the pedal 11 by latching with ratchet 15 (FIG. 13).
By this rotation, the brake cable 16 is drawn out to brake whereby the ratchet 15 latches with a lock pawl 19. In this state, when the foot is separated from the pedal 11, the pedal 11 returns to its original position by aid of a return spring 14 as shown in FIG. 14. However, the ratchet 15 is retained at the position after rotation by latching with the lock pawl 19 to maintain a braking state (brake maintaining state).
In this case, when the first step on the brake fails to produce an effective braking, a second stepping is necessary to effectively brake.
Further, the release of the above braking state is performed by releasing the latching ratchet 15 with the lock pawl 19 by pulling a release cable 20. By this release, the ratchet 15 returns to its original position (FIG. 10) by aid of the pulling force of the brake cable 16 to maintain the initial state. Since the pedal 11 is already returned to the original position at the time of the return of the ratchet 15, a shocking return operation of the pedal 11 does not occur and a stable operation is obtained.
However, since the brake retaining state in the conventional pedal parking brake device is obtained by latching ratchet 15 with lock pawl 19, it is impossible to retain the maximum braking position in spite of the fact that pedal stepping position is a maximum brake position, and the ratchet 15 returns in the return direction by 1 pitch of the ratchet 15 in order to latch with lock pawl 19 and also the brake cable 16 returns in the same direction. Accordingly, the conventional pedal parking brake device has such a difficult problem obtaining a brake retaining state at the maximum braking position.
Further, if the pitch of the ratchet 15 lessens, the amount of return of the ratchet 15 and the brake cable 16 can be decreased. However, if the pitch lessens too much, the teeth portion of the ratchet 15 decreases in strength, which becomes impractical.
This invention is performed in view of this problem. The object of this invention is to provide a pedal parking device which can obtain a brake retaining state at the maximum brake position.